Unusual sensory experiences are present in 69 percent of children with autism (Baranek et al., 2006), and these are thought to have negative consequences on development, adaptive behavior, and family functioning. These features are behaviorally expressed as 3 sensory response patterns (hyporesponsive, hyper- responsive, sensory seeking). The purpose of this project is to explain the developmental course, functional impact, and pathogenesis of these unusual features with implications for early detection and intervention. Our specific aims are to: 1) determine the developmental course of unusual sensory features in children with autism and DD; 2) measure the functional impact of sensory features in children with autism on their adaptive and maladaptive behaviors as well as family functioning; and 3) isolate specific neurocognitive and contextual risk factors that are associated with the expression of usual sensory features. Four interrelated studies (total n=185) will address these aims. Study 1 (prospective longitudinal design) uses an existing cohort to examine stability of sensory features from the preschool (2-6 yrs) to the school-age (6-12 yrs.) period, and the functional impact of these features on child/ family outcomes. Study 2 employs retrospective video analysis to identify precursors of sensory features in children with autism during infancy (9-18 months), differentiate these from controls, and predict to preschool/school-age developmental outcomes. Study 3 uses in-home behavioral observations to determine the environmental contexts that elicit unusual sensory responses. Lab measures and personal accounts of parents and verbal children will complement the in- home study to further elucidate the impact of sensory features on family functioning in daily life. Study 4 uses electrophysiology (ERP) to test neurocognitive mechanisms (sensory detection, discrimination, involuntary orienting) that are predicted to underlie specific sensory phenotypes. Thus, in a subgroup of children, convergent data from 4 developmental time points (early infancy, later infancy, preschool and school years) will be secured to study change trajectories in sensory features in autism using mixed methods. Our findings may have implications for understanding brain-behavior linkages, early risk markers of unusual sensory features and their developmental course, and novel intervention strategies that may improve child and family functioning. [These aims are consistent with NIH Autism Research Matrix priorities #16, 19, 22, 23 & 26.] [unreadable] [unreadable] [unreadable]